A rare earth metal-containing flux-cored wire for x80 pipeline steel

Abstract

The present application relates to a kind of rare earth metal-containing powder core flux-cored wire for X80 pipeline steel, belong to the technical field of flux-cored wire for gas protection.The rare earth metal-containing powder core flux-cored wire for X80 pipeline steel is composed of carbon steel strip and metal powder core, the metal powder core is composed of the following raw materials by weight percentage, medium carbon manganese iron 10-15%, nickel powder 10-15%, 75 ferrosilicon 4-8%, ferromolybdenum 4-6%, ferrotitanium 1-3%, yttrium oxide 2-5%, aluminum magnesium alloy 1-3%, and the balance is iron powder.The beneficial effect is that the Si-Mn-Mo-Ni alloy system welding wire can be used for the backing welding, filling welding and cap welding of X80 low alloy high strength steel, there is basically no spatter during welding, and full position welding can be realized, the low temperature toughness is good, and the diffusion hydrogen content is extremely low.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flux-cored wires for gas shielding, and particularly relates to a rare earth metal-containing powder core flux-cored wire for X80 pipeline steel. BACKGROUND

[0002] In long-distance natural gas pipelines, in order to increase the throughput and reduce the cost of pipe materials, a pipeline steel pipe with a higher grade is usually selected. X80 pipeline steel is widely used in the field of pipeline steel at present due to its high strength, good plasticity and toughness, and welding performance, and is the main pipeline steel grade of the West-to-East Gas Pipeline Project in China and will still be the main force of long-distance pipelines for a long time to come.

[0003] Welding is an important link in the application of pipeline steel, and the welding construction of pipeline steel has experienced a transformation process from manual arc welding to semi-automatic welding and automatic welding, and the development speed is very fast. Field experience shows that pipeline failures often occur in the weld zone. On the one hand, the welded joint often shows brittle fracture in the service process due to insufficient low-temperature toughness, which poses a great threat to life and property safety; on the other hand, hydrogen is often introduced into the weld during the welding process, and excessive diffusible hydrogen is often closely related to the generation of hydrogen-induced cracks. Therefore, obtaining a weld with stronger comprehensive mechanical properties is very crucial for the application of pipeline steel.

[0004] CN202110104114.0 is a low-temperature phase change flux-cored wire suitable for X80 pipeline steel and a preparation method thereof. The alloy system of the flux-cored wire is Si-Mn-Ni-Cr, and trace elements are V, Ti and Cu. No rare earth element is added in the powder core. The Charpy impact energy at -40 DEG C is 100 J, and the diffusible hydrogen content of the weld is not mentioned.

[0005] CN202110105191.8 is a high-toughness gas shielding flux-cored wire for X80 pipeline steel and a preparation method thereof. The alloy system of the flux-cored wire is Si-Mn-Ni, and trace elements are V, Ti, Cu and Al. No rare earth element is added in the powder core. The impact energy at -45 DEG C is 150 J, and the diffusible hydrogen content of the weld is not mentioned. SUMMARY

[0006] The application provides a rare earth metal-containing powder core flux-cored wire for X80 pipeline steel, which adopts a Si-Mn-Mo-Ni alloy system flux-cored wire and can be used for backing welding, filling welding and cap welding of X80 low-alloy high-strength steel. The flux-cored wire basically has no spatter during welding, can realize all-position welding, has good low-temperature toughness, and has very low diffusible hydrogen content.

[0007] The technical scheme for solving the above technical problems of the present application is as follows: a rare earth metal-containing powder core flux-cored wire for X80 pipeline steel is composed of a carbon steel strip and a metal powder core, the metal powder core is composed of raw materials in the following weight percentages: medium-carbon manganese iron 10-15%, nickel powder 10-15%, 75 silicon iron 4-8%, molybdenum iron 4-6%, titanium iron 1-3%, yttrium oxide 2-5%, aluminum-magnesium alloy 1-3%, and the balance being iron powder.

[0008] Beneficial effects:

[0009] Compared with other rare earth metal-containing powder core flux-cored wires for X80 pipeline steel, the present wire comprehensively considers the wire process performance and the mechanical properties of the weld metal, and a Si-Mn-Mo-Ni alloy system wire is designed, which can be applied to the backing welding, filling welding and cap welding of X80 low-alloy high-strength steel. During welding, there is basically no spatter, and full-position welding can be achieved, the low-temperature toughness is good, and the diffusible hydrogen content is extremely low.

[0010] Preferably, the metal powder core is composed of raw materials in the following weight percentages: medium-carbon manganese iron 10%, nickel powder 15%, 75 silicon iron 4%, molybdenum iron 6%, titanium iron 3%, yttrium oxide 2%, aluminum-magnesium alloy 1%, and iron powder 59%.

[0011] Preferably, the metal powder core is composed of raw materials in the following weight percentages: medium-carbon manganese iron 15%, nickel powder 10%, 75 silicon iron 4%, molybdenum iron 6%, titanium iron 1%, yttrium oxide 4%, aluminum-magnesium alloy 2%, and iron powder 58%.

[0012] Preferably, the metal powder core is composed of raw materials in the following weight percentages: medium-carbon manganese iron 12%, nickel powder 13%, 75 silicon iron 6%, molybdenum iron 5%, titanium iron 2%, yttrium oxide 3%, aluminum-magnesium alloy 3%, and iron powder 56%.

[0013] Preferably, the purity of the yttrium oxide is greater than 99%.

[0014] Preferably, the carbon steel strip is a 12mm*0.5mm cold-rolled carbon steel low-sulfur phosphorus steel strip.

[0015] Formula analysis of the present application:

[0016] The following is an explanation of the types and contents of various powders in the core of the present application.

[0017] Medium carbon ferromanganese is the main deoxidizer, which reduces the oxygen content in the weld to reduce the number of inclusions, and transits C and Mn to the weld. The content of C element has a significant impact on the strength of the weld. A small amount of C content can make the yield strength increase by 50-150 MPa, but too much C will significantly reduce the low-temperature toughness of the weld structure, so the amount needs to be controlled to obtain the appropriate strength. Mn element is a strong toughening element. Appropriate amount of Mn element can improve the high-temperature toughness while improving the strength. When Mn is excessive, segregation is easy to occur, thereby reducing the mechanical properties of the weld. Therefore, when designing the content of medium carbon ferromanganese, the content of C and Mn elements in the weld and the deoxidizing effect should be fully considered, and the appropriate weight of medium carbon ferromanganese powder should be set.

[0018] Nickel powder is mainly responsible for transiting Ni element to the weld. The addition of Ni element can refine the structure and promote the formation of acicular ferrite. Ni element can also significantly reduce the ductile-brittle transition temperature of the weld, but Ni and Mn interact with each other, so the addition of Ni should be based on the amount of Mn element added.

[0019] 75 Ferrosilicon: Ferrosilicon is another important deoxidizer, which is also responsible for transiting Si element to the weld. Appropriate ferrosilicon can improve the process performance of the welding wire, improve the strength of the weld metal, and Si / Mn has a great influence on the microstructure of the weld, so the weight of medium carbon ferromanganese powder needs to be considered when considering the amount of ferrosilicon powder added.

[0020] Molybdenum iron can transit Mo to the weld to improve the strength of the weld.

[0021] Titanium iron can not only be used as a deoxidizer, but also transit Ti element to the weld. A small amount of Ti element can form Ti-containing inclusions, which act as nucleation sites for acicular ferrite, thereby improving the strength and toughness of the weld.

[0022] Yttrium oxide powder is used to transit Y element to the weld. Appropriate Y element can significantly reduce the diffusible hydrogen content of the weld. In addition, appropriate Y element can also improve the strength and toughness of the weld structure, but excessive yttrium oxide powder not only affects the process performance and produces a large amount of spatter, but also easily segregates and reduces the mechanical properties of the weld.

[0023] Aluminum-magnesium alloy is an important deoxidizer. Appropriate Al element can improve the strength of the weld.

[0024] The mass of the above metal powder core accounts for 15-17% of the total mass of the welding wire.

[0025] Principle:

[0026] The main alloy system of the welding wire is C-Si-Mn-Ni-Mo, and the micro-alloy elements are Y and Ti. The trace rare earth element Y can replace Si and Mn to play a deoxidizing role, reduce the oxygen content in the weld, and reduce the number of large-size oxide inclusions in the weld. On the other hand, unlike the addition of fluorinated rare earth, the Y element in the Y2O3 powder can transition into the weld. The Y element in the weld can modify the inclusions, spheroidize and refine the inclusions, and is beneficial to the formation of fine acicular ferrite, thereby reducing the content of proeutectoid ferrite in the weld, improving the strength and low-temperature toughness of the weld, and the impact energy value at-40℃ can reach more than 135J, having good low-temperature toughness. In addition, the Y-containing inclusions in the weld are also irreversible hydrogen traps with large hydrogen binding energy, which can capture hydrogen, thereby reducing the content of diffusible hydrogen in the weld. The diffusible hydrogen content detected in the deposited metal is less than 2.5mL / 100g, which is beneficial to improving the hydrogen embrittlement resistance of the weld and prolonging the service life of the weld in an acidic environment.

[0027] The application also provides a method for welding by using the flux-cored wire as described above, and the welding conditions are that the protective gas is composed of 75-85% Ar and 15-25 CO2 by volume content, the interlayer temperature is 80-120℃, the welding current is 240A, the welding voltage is 28V, and the welding speed is 0.25m / min.

[0028] The application also provides an application of the flux-cored wire as described above in X80 pipeline steel. DETAILED DESCRIPTION

[0029] The principles and characteristics of the application are described below, and the examples are only used to explain the application and not to limit the scope of the application.

[0030] Example 1

[0031] A rare earth metal-containing powder core flux-cored wire for X80 pipeline steel is composed of a carbon steel strip and a metal powder core, and the metal powder core is composed of raw materials with the following weight percentages: medium-carbon manganese iron 10%, nickel powder 15%, 75 silicon iron 4%, molybdenum iron 6%, titanium iron 3%, yttrium oxide 2%, aluminum-magnesium alloy 1%, and iron powder 59%. The mass of the metal powder core accounts for 15.5% of the total mass of the welding wire.

[0032] The welding conditions are that the protective gas is composed of 75-85% Ar and 15-25 CO2 by volume content, no pre-welding and post-welding heat treatment is required, the interlayer temperature is 80-120℃, the welding current is 240A, the welding voltage is 28V, and the welding speed is 0.25m / min.

[0033] The tested welding wire has good process performance, stable welding arc, no spatter, and the weld appearance is good without defects such as porosity, slag inclusion and incomplete fusion.

[0034] The deposited metal component detection is as follows: C 0.055%, Mn 1.55%, Si 0.23%, Ni 1.02%, Mo 0.23%, Y 0.05%, Ti 0.02%, and the balance is Fe.

[0035] The mechanical properties of the deposited metal are as follows:

[0036]

[0037] Example 2

[0038] A rare earth metal-containing flux-cored wire for X80 pipeline steel is composed of a carbon steel strip and a metal core, and the metal core is composed of raw materials with the following weight percentages: medium-carbon manganese iron 15%, nickel powder 10%, 75-silicon iron 4%, molybdenum iron 6%, titanium iron 1%, yttrium oxide 4%, aluminum-magnesium alloy 2%, and iron powder 58%.

[0039] The welding conditions are as follows: the protective gas is composed of 75-85% Ar and 15-25% CO2 by volume, no pre-welding and post-welding heat treatment is needed, the interpass temperature is 80-120℃, the welding current is 240A, the welding voltage is 28V, and the welding speed is 0.25m / min.

[0040] The tested welding wire has good process performance, stable welding arc, no spatter, and the weld appearance is good without defects such as porosity, slag inclusion and incomplete fusion.

[0041] The deposited metal component detection is as follows: C 0.065%, Mn 1.75%, Si 0.25%, Ni 0.89%, Mo 0.23%, Y 0.08%, Ti 0.02%, and the balance is Fe.

[0042] The mechanical properties of the deposited metal are as follows:

[0043]

[0044] Example 3

[0045] A rare earth metal-containing flux-cored wire for X80 pipeline steel is composed of a carbon steel strip and a metal core, and the metal core is composed of raw materials with the following weight percentages: medium-carbon manganese iron 15%, nickel powder 10%, 75-silicon iron 4%, molybdenum iron 6%, titanium iron 1%, yttrium oxide 4%, aluminum-magnesium alloy 2%, and iron powder 58%.

[0046] The welding conditions are as follows: the protective gas is composed of 75-85% Ar and 15-25% CO2 by volume, no pre-welding and post-welding heat treatment is needed, the interlayer temperature is 80-120℃, the welding current is 240A, the welding voltage is 28V, and the welding speed is 0.25m / min.

[0047] The welding wire has good process performance, stable welding arc, no spatter, and the weld appearance is good without defects such as porosity, slag inclusion and incomplete fusion.

[0048] The deposited metal has the following components by weight percentage: C 0.06%, Mn 1.65%, Si 0.34%, Ni 0.95%, Mo 0.23%, Y 0.1%, Ti 0.02%, and the balance of Fe.

[0049] The mechanical properties of the deposited metal are as follows:

[0050]

[0051] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0052] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A rare earth metal containing flux cored wire for X80 pipeline steel, consisting of a carbon steel strip and a metal powder core, characterized in that, The metal powder core is composed of raw materials with the following weight percentages: medium-carbon ferromanganese 15%, nickel powder 10%, 75 ferrosilicon 4%, ferromolybdenum 6%, ferrotitanium 1%, yttrium oxide 4%, aluminum-magnesium alloy 2%, and iron powder 58%.

2. The rare earth metal-containing powder core flux cored wire for X80 pipeline steel according to claim 1, characterized by, The purity of the yttrium oxide is greater than 99%.

3. The rare earth metal-containing powder core flux cored wire for X80 pipeline steel according to claim 1, characterized by, The carbon steel strip is a 12mm*0.5mm cold-rolled carbon steel low-sulfur phosphorus strip.

4. A method of welding using the flux cored wire according to any one of claims 1 to 3, characterized by, The welding condition is that the protective gas is composed of 75-85% Ar and 15-25% CO 2 in volume content, the interlayer temperature is 80-120℃, the welding current is 240A, the welding voltage is 28V, and the welding speed is 0.25m / min.

5. Use of the flux-cored wire according to any one of claims 1-3 in X80 pipeline steel.

Images